Abstract
Low-cost, miniaturized hyperspectral imaging technology is becoming available for small unmanned aerial vehicle (UAV) platforms. This technology can be efficient in carrying out small-area inspections of anomalous reflectance characteristics of trees at a very high level of detail. Increased frequency and intensity of insect induced forest disturbance has established a new demand for effective methods suitable in mapping and monitoring tasks. In this investigation, a novel miniaturized hyperspectral frame imaging sensor operating in the wavelength range of 500–900 nm was used to identify mature Norway spruce (Picea abies L. Karst.) trees suffering from infestation, representing a different outbreak phase, by the European spruce bark beetle (Ips typographus L.). We developed a new processing method for analyzing spectral characteristic for high spatial resolution photogrammetric and hyperspectral images in forested environments, as well as for identifying individual anomalous trees. The dense point clouds, measured using image matching, enabled detection of single trees with an accuracy of 74.7%. We classified the trees into classes of healthy, infested and dead, and the results were promising. The best results for the overall accuracy were 76% (Cohen’s kappa 0.60), when using three color classes (healthy, infested, dead). For two color classes (healthy, dead), the best overall accuracy was 90% (kappa 0.80). The survey methodology based on high-resolution hyperspectral imaging will be of a high practical value for forest health management, indicating a status of bark beetle outbreak in time.
Highlights
Forest ecosystems are annually faced with incremental disturbances by native and non-indigenous insect pests in the boreal zone [1]
A novel miniaturized hyperspectral frame imaging sensor was used to identify mature Norway spruce trees suffering from infestation by the invasive bark beetle I. typographus
We developed a processing approach for analyzing spectral characteristics for high spatial resolution photogrammetric and hyperspectral image data in a forested environment, as well as for identifying damaged trees
Summary
Forest ecosystems are annually faced with incremental disturbances by native and non-indigenous insect pests in the boreal zone [1]. According to the projections of climatic change impacts, distribution of forest pest insects, as well as insect-induced damage will gradually shift towards northern latitudes. This climate-driven phenomenon has already been evident with pine sawflies [2,3], moths [4,5] and bark beetles [6,7]. And temporally significant outbreaks of bark beetles, associated with the Norway spruce Since the year 2010, with a high accumulated temperature, the European spruce bark beetle Since the year 2010, with a high accumulated temperature, the European spruce bark beetle (Ips typographus L. (I. typographus))
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